A Negative Income Tax (NIT) is an example of tax expenditure, from which is possible to ensure a minimum income to every citizen. In this paper I consider the impact of a tax whit this characteristic on disposable income, poverty, and inequality of alternative designs. Efficiency and equity can guide an assessment of a tax system or a policy of incomes transfers. This paper focuses on the second criteria, for which I realize static arithmetic microsimulation. I conclude that the main virtue of applying an NIT is articulate the income policies, while the main impact on welfare are observed when simulation scenarios allow increase the tax rate applied to the bands higher income while keeping the total tax raised.